Here are a number of weather related links to help you predict cloud conditions, seeing conditions and space weather.
Includes animation link. Drop down menu also has links for clouds including forecast for day and night
Predicting Seeing Conditions: This page includes a forecast for seeing conditions for the entire North American Continent. The page is set up just like a satellite weather page including animations. It also includes a guide for numerically recording conditions.
Weather and Clear Sky Clock for St. Louis.
Instant Sun/Moon rise and set table (as well as twilight) from USNO.
Space Weather: Offers alerts and predictions for aurora, meteor showers and other space phenomena that can have impact on the Earth's weather system
Visible, infrared, etc.
Great for clouds
Interactive sky maps - printable: St. Louis is about 39 N latitude and 90 W longitude.